The present invention concerns a treating system of exhaust gas such as PFC gas, etc., more specifically an exhaust gas treating system for decomposing and treating harmful matters contained in the exhaust gas by means of plasma generated between electrodes.
Conventionally, proposal is made of exhaust gas treating systems for decomposing and treating harmful matters contained in the exhaust gas means of plasma generated between electrodes (for example, Japanese Laid-open Patent Publication No. H5-15737 (patent literature 1), Japanese Laid-open Patent Publication No. H7-47224 (patent literature 2), Japanese Laid-open Patent Publication No. H11-156156 (patent literature 3), and Japanese Laid-open Patent Publication No. 2004-209373 (patent literature 4)).
Of those inventions, the exhaust gas treating system described in the patent literature 4 comprises a reaction tube in the shape of a slender pipe through which to pass the gas to be treated, a high-tension electrode disposed on the top side of this reaction tube, a grounding electrode on the bottom side of this reaction tube, a feed water pipe for feeding water into said reaction tube from the top side of the reaction tube, an exhaust pipe for discharging the water in the reaction tube from the bottom side of the reaction tube, and a nozzle for feeding electrolytic solution into the reaction tube from the top side of the reaction tube, wherein the plasma is generated in the axial direction of the reaction tube, thereby enabling to decompose and treat harmful matters contained in the exhaust gas more efficiently compared with the exhaust gas treating systems described in the patent literatures 1˜3.
By the way, in this exhaust gas treating system described in the patent literature 4, the generation of plasma is made by forming a water membrane on the inner side of the reaction tube, and flowing an electrolytic solution there.
However, according to such construction, the electrodes must inevitably be disposed in the vicinity of the reaction tube, and this makes it impossible to increase the diameter of the reaction tube to beyond a certain level, thus presenting a problem of limited exhaust gas treating volume.
Moreover, with conventional exhaust gas treating systems, in which a water membrane is formed in the reaction tube, the state of generation of plasma becomes unstable because of shaking of the water wall, making it impossible to extend the distance between electrodes (plasma length) to beyond a certain level, and thereby further limiting the harmful matters removing performance.